NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, operated by the Alliance for Sustainable Energy, LLC.

Eastern Renewable 

Generation Integration 

Study Solar Dataset

Marissa Hummon

February 26, 2014

UVIG Forecasting Workshop

Tuscan, Arizona

NREL/PR-6A20-61498
2

ERGIS Solar Data Set

Objective: 

Develop a data set is for grid integration studies – 

meant to mimic the operating conditions of a dayahead SCUC, intra-day UC, and 5-minute SCED

Dataset:

o 5-minute “actual” solar power data

o Day-ahead solar power forecast

o Four-hour-ahead solar power forecast
3

ERGIS Scenarios

Eastern Renewable Generation 

Integration Study (ERGIS): How do 

high penetrations of solar and wind 

generation impact system operations 

of the Eastern Interconnection?

• Scenarios are designed to 

bookend two approaches to 

renewables 

– National policy implementation

– Regional policy implementation

 Energy 

Penetration (%)

Solar PV 

Capacity (GW)

Wind 

Capacity (GW)

Conventional 

Capacity (GW)

Scenario Solar Wind Rooftop Utility Onshore Offshore Nuclear Coal CC CT

Low Renewables 0 3 0 0 23 0 88 208 185 187

State RPS 0.2 12 1 2 95 8 88 195 175 198

Regional 30% 10 20 70 104 149 27 88 182 154 145

National 30% 5 25 35 52 199 16 88 171 173 153
4

Rooftop and Utility PV Locations in ERGIS

4
5

Motivation

NREL PIX 18625, Peter McNutt, Guam
6

Motivation

Source: Clean Power Research 

SolarAnywhere

http://www.cleanpower.com/produ

cts/solaranywhere/sa-data/
7

Motivation

Source: NREL Measurement and 

Instrumentation Data Center (MIDC)

http://www.nrel.gov/midc/ 

Source: Clean Power Research 

SolarAnywhere

http://www.cleanpower.com/produ

cts/solaranywhere/sa-data/
8

Site Clearness Index Analysis

Spatial satellite data is used to calculate the relative proportions of cloud cover in an 

area for each hour. This data is related to the sub-hourly measurements of 

irradiance. These figures show five consecutive hours of aerial satellite data (left) 

and corresponding minutely ground-based irradiance data (right). 
9

Synthesis of 1-minute Solar Data
10

Site-to-site correlations
11

Solar Forecast Data Comparison

• Day-ahead

o WRF

o Persistence

• 4-Hour-ahead

o WRF

o Persistence

NREL’s HPC resource: Peregrine 

(above)

NREL’s WRF study area (left)

Persistence forecast (below)
12

Day-ahead Solar
13

Day-ahead Solar
14

Day-ahead Solar
15

Day-ahead Forecast Error

15
16

Day-ahead Hourly Ramp Forecast Error

16
17

Bias in the WRF data

17
18

Bias in the WRF data

18
19

Mapping Forecast Errors

19

WWSIS Forecast Errors Model Production Forecast Errors

95% 

95% 

Normalized Forecast Error Normalized Forecast Error

-1 0 1 -1 0 1
20

Day-ahead Solar
21

Day-ahead Forecast Error Correction

21
22

Day-ahead Hourly Ramp Forecast Error

22
23

4-hour-ahead Solar
24

4-hour-ahead Solar
25

4-hour-ahead Solar
26

4-Hour-Ahead Forecast Error

26
27

4-Hour-Ahead Hourly Ramp Forecast Error

27
28

ERGIS Solar Data Summary

NREL will be releasing (at the end of March!):

• 5-minute solar power “actuals”

• Hourly day-ahead from WRF model with statistical correction

• Hourly “four-hour-ahead” for clear power index persistence

Team:

 Andrew Weekley

Caroline Draxl

 Anthony Florita

Bri-Mathias Hodge

Aaron Bloom

Jack King

Marissa Hummon

More information about the ERGIS 

study can be found at:

http://www.nrel.gov/electricity/tra

nsmission/eastern_renewable.html